Cold Developers

There are many methods for controlling the range of densities on a black and white negative. For example, highly diluted 'pre-developers' used in conjunction with development in normal concentration.

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I was thinking that, since the rate of chemical reaction between the silver on the film and the developer is dependent on the temperature of the developer as well as concentration and time, one should be able to control the magnitude of development in shadow areas relative to highlight areas through a period of development in a cold developer solution. Development in a solution at normal temperature may be used to bring up highlight areas after shadows have come to full development in the cold solution.

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I have never tried this and there may be no advantage to doing so. I thought I'd ask about it because someone out there may have tried it. Any thoughts on the matter are appreciated.

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Regards,

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Jason

A cold developer will slow development in the shadows and highlights

to the same degree, as will using a shorter time. Dilute developers

can give highlight compensation, but a cold developer will not.

"A cold developer will slow development in the shadows and highlights

to the same degree, as will using a shorter time." This is true only

if the activation energy for the chemical reactions of developing the

shawdows and highlights is equivalent. Does anyone know if this is

true? (Warning, potentially irrelevant credential info follows: I'm

a Ph.D. physical organic chemical whose dissertation centered on

elucidating reaction mechanisms.)

I am under the impression that using a shorter development time does

not reduce densities to the same degree in shadows and highlights.

It seems to me that the Zone System depends on greater reduction in

highlight areas as opposed to shadow areas with reduced development

time and greater build-up up density in highlights as opposed to

shadows with increased development time. I know that shadows come to

full development long before highlight areas.

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I am also under the impression that the activation energy required in

shadow areas is less than that for highlights. [Disclaimer: I may be

way off here, the truth is, I don't know this to be a fact.] But, it

makes sense to me that this would be the case.

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Regards,

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Jason

No scientific evidence (at least, of a rigorous naturee) to back this

up. But I believe that rate of development is generally slowed

uniformly (at the least, any difference that is there does not seem

useful in control terms). So, at the risk of generalizing and

ignoring other interactions in the process, reducing time and

temperature will affect shadows and highlights proportionally. In my

opinion, dilution also reduces activity proportionally across shadows

and highlights. However, some compensation is possible with dilution

because of the barrier in the form of the emulsion which leads to

local increases in development byproducts (note: obviously developer

formulation is a critical factor in this generalization - a lith

developer, for e.g., will increase contrast locally since the

reaction byproducts increase activity). However, the biggest uses of

dilution, in my experience, is not the slight compensation it confers

from the emulsion barrier slowing diffusion. By slowing the rate of

development (viz., increasing time), it allows one to use much lower

levels of agitation (once every three minutes instead of every

minute) and this compensation is much greater than any inherent

compensation due to dilution itself. Caveats: These conclusions

reached by testing Arista 125 with various dilution and agitation

patterns in HC110. Make of it what you will. Cheers. DJ

Maybe I did not say it right above. What I meant was making a

developer colder is often the same as making the time shorter. A

lower temperature slows down the process. If the developer contains

hydroquinone and metol, I have heard that the activity of these

agents is not exactly the same at different temperatures, so contrast

may vary a bit with some developers.

Various developing agents and other agents (such as sodium sulfite)

have different sensitivities to temperature. For example, if I

remember right, hydroquinine becomes completely ineffective at lower

temperatures.

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Thus changing the temperature far from normal is, in effect,

reformulating your developer. And, of course, this can dramatically

change your characteristic curve.

A lot of speculation!, Like the man said, TRY IT! And let us

know how it comes out. Pat

All I know is that with paper developer, using really cold developer

after the basic image has come up will make for very easy, repeatable

and controllable solarized prints.

The developer works at a constant rate depending on temperature. The

reason that a colder temperature would not work as a compensating

factor is because of the nature of the siver within the emulsion. The

sivler halides in the emulsion at exposure are energized in direct

relation to how much light hit them. The shadow values have the least

energy imparted to them. Few silver halide crystals were hit. The

silver halides in the highlights were activated to a much greater

extent. When the film is emersed in the developer and the emulsion

saturated the less energized(fewer silver halides struck) areas

develope at the same rate as the highlights. But the shadow areas

quickly become completely developed. There is no more silver to

convert. The highlights continue to develope. As the midtones develope

out and all the energized silver is converted those areas are finished

and only the areas with the most silver energized continues to

develope until those areas also finish developing with no more silver

to convert. So the colder temps only slow down the entire process at

the same rate until the difference is great enough to inhibit some

developers from working at all. Raising the temps works in the

opposite direction. But the same steps occur just at a faster rate.

The idea behind compensating developers or water bath systems is that

the emulsion holds only a certain amount of chems and these are

exhausted at a certain rate. So the silver is still converted at the

same rate but the highlight densities use all the developer just as

quickly exhausting it. The act of agitation renews the developer in

all areas but the shadows have no silver left to convert so all that

is left is the conversion of the silver in the higher densities.

Agitation and time are the only two variables left. Don't agitate a

lot and you can control the conversion of silver at a steady rate.

Leave it in longer and you get the same thing. James